Functionalized silicon substrates with stripe-patterned surface-near electrostatic forces for the self-organized, stable immobilization of biomolecules

Highlights: • Characterization of surface-near electrostatic forces above Si pn-junctions. • Measurement of Kelvin bias on the nanoscale in dark and under illumination. • Calculation of Kelvin bias variation over Si pn-junctions in dark. • Comparison between measured and calculated Kelvin bias variation. • Demonstration of self-organized molecular immobilization (DNA, bovine proteins). Silicon substrates with stripe-patterned surface-near electrostatic forces (SNEF) were prepared by local implantation of boron ions into n-type silicon wafers and of phosphorus ions into p-type silicon wafers in a stripe pattern of 12 μm periodicity. The dependence of SNEF on the concentration of implanted ions, post-annealing conditions, and generation of charge carriers under illumination was investigated by measuring the 1st and 2nd harmonics of the SNEF in the dark and under illumination using Kelvin probe force microscopy. The self-organized immobilization of biomolecules on silicon regions with positive charges occupying the interface states between the silicon and the native SiO₂ has been demonstrated for the negatively charged single stranded deoxyribonucleic acid (DNA) and bovine serum albumin (BSA) proteins.